Compact high capacity gas burner



y 9 i A. L. MILLER I 7 3,446,566

' COMPACT HIGH CAPACITY GAS BURNER Filed May 1, 1967 INVENTOR. 11 4 1. 44/4458 I W .4444

United States Patent US. Cl. 431349 6 Claims ABSTRACT OF THE DISCLOSURE A narrow, elongated, sheet metal gas burner of rectangular cross section with the major axis vertical and burner orifices spaced along its horizontal top surface, the burner orifices being each formed from H configuration slits with the legs of the H extending longitudinally of the burner, and with the tabs interiorly of the legs of the slit bent upwardly at acute angles to define the major fuel flow orifice therebetween. The restricted corners where the tabs join the top wall of the burner lower the velocity of the fuel flowing therethrough to maintain the burner flame under conditions of high velocity flow through the main orifice opening.

Background of the invention The invention relates to burners for gaseous fuel for use in furnaces and heaters generally, and more particularly, to compact, high-capacity gas burners employing high-velocity fuel flow through spaced orifices.

Compact, elongated, sheet metal gas burners are known in the prior art and resemble the burner of the present invention, except with respect to the burner orifices. These prior art burners have, in common with the burner of this invention, sheet metal construction, light-weight and com pact size, but have been sharply limited in capacity because increasing the volume of fuel flow by increasing its velocity has resulted in blowing out the burner flame. One burner known in the prior art has used truncated, dome-like extrusions from the top surface of the burner with round holes as orifices through which the fuel mixture has passed with substantially uniform velocity within the jet. This velocity cannot exceed the speed of propagation of ignition back along the fuel mixture, as otherwise flame-out occurs as the burning mixture moves further away from the burner until the fire is extinguished. The capacity of these burners is thereby sharply restricted. 6

Summary of the invention It is the object of the present invention to increase the heating capacity of compact gas burners by increasing the volume and velocity of the fuel mixture fed from the orifices thereof, while maintaining ignition and preventing flame-out.

The main flow of the fuel mixture is at a velocity much greater than the speed of ignition back along the fuel, but flame-out is prevented by slowing a portion of the fuel mixture so that it is fed along with the main volume, but at a much lower velocity which is within the capability of the speed of propagation of ignition to maintain a flame, so that the flame from the slower moving, minor portion of the fuel mixture continually ignites and maintains burning of the main high-velocity fuel jet.

Such high capacity operation is accomplished in the burner of the present invention by using a composite, nonuniform orifice having a central, free, main opening through which a jet of fuel mixture passes at high velocity, and restricted portions which slow up the fuel mixture passing therethrough to a velocity within the capability of the speed of propagation of ignition back along the flow. Such non-uniform orifices may take many configurations 3,446,566 Patented May 27, 1969 within the general concept of this invention, but, in the simple preferred embodiment, are formed in sheet metal by simple slitting and bending operations forming an unrestricted open orifice between tabs for the main high-velocity jet flow, and restricted angular openings at the sides of the tabs through which the fuel mixture is slowed to a velocity low enough to sustain a flame in the slower moving fuel mixture which will, in turn, maintain the main highvelocity jet ignited.

Brief description of the drawing FIGURE 1 is a perspective view of a compact highvelocity gas burner according to the present invention;

FIGURE 2 is an enlarged, partial, sectional view through a pair of burner orifices taken at the line 2-2 of FIG- URE 1;

FIGURE 3 is a transverse vertical sectional view on the line 3-3 of FIGURE 1;

FIGURE 4 is a plan view of a burner orifice in the direction of the arrows 4; and

FIGURE 5 is a plan view of a form of slitting of the sheet metal top wall of the burner from which the orifices are formed.

Description of the preferred embodiment In the preferred embodiment of the invention selected for illustration and specific description herein, the main :body 11 of the burner is formed of thin sheet metal bent into a hollow, rectangular configuration joined together by brazing or welding at 12. The burner is of elongated configuration, as shown in FIGURE 1, so as to space a plurality of orifices 13 along its top wall and has its bottom wall 14 inclined upwardly toward the closed end 20 to progressively reduce the area of the internal chamber 15 and maintain the fuel mixture chamber 15 in the body of the burner beneath the orifices 13 at substantially constant pressure along its length so that the jets of fuel mixture issue from the burner orifices 13 at substantially the same velocity. The entrance 16 of the burner chamber 15 is open and a gas nozzle 17 projects gaseous fuel into the chamber 15, entraining primary air therewith through the open end 16 to provide a fuel mixture of gas and air under pressure in the chamber 15. The burner has a top wall 18, side walls 19 and 20, and bottom flanges joined together at 12 to form the bottom wall 14.

A portion of a sheet metal blank from which the burner is formed, taken around one of the orifices 13 to be, is shown in FIGURE 5 at 22. This blank will provide the top wall 18 and side walls 19 and 20 when bent along the interrupted lines 23 and 24, respectively. That portion which is to form the top wall 18 is cut through or slit to form elongated slits 25 and 26 parallel to the longitudinal axis of the burner and disposed adjacent the opposite top corners where the burner top wall joins the side walls thereof. A third slit 27 transverse of the top wall 18 joins substantially the mid-portions of the slits 25 and 26, the resultant configuration of the slits 2527 being H shaped, with the legs of the H extending longitudinally of the burner and adjacent the top corners thereof. Between the slits 25 and 26, at opposite sides of the transverse slit 27, are the integral tabs 28 and 29 which are bent upwardly at acute angles, as illustrated in the figures of the drawing, to form the main burner orifice 31 therebetween in unrestricted communication with the burner chamber 15. The orifice 31, between the inclined walls of the tabs 28 and 29, functions much as a nozzle and passes the fuel mixture therethrough in large volume at high velocity, as indicated by the arrow 32. This is the main volume fuel jet which gives to the burner its high capacity. Fuel will also flow from chamber 15 beyond the side edges of the tabs 28 and 29 and this flow will be at lower velocity and will be most restricted at the corners where the tabs 28 and 29 join the top wall 18 at the flow portions indicated by the arrows 33. This slowest moving fuel mixture follows the main jet 32, but at much lower speed, and, as stated before, within the capability of the speed of propagation of ignition back along the flow to maintain a flame in the slower moving gas 33. The flame from this slower moving gas, which is self-propagating, maintains ignition of the high-velocity jet 32 and therefore permits the burner to operate at high capacity without flame-out.

As a result of this invention, high-capacity heat input may be secured with relatively small over-all heater size, since the compactness of the burners permits them to be located side-by-side in a relatively small space and the high velocity of the main fuel jets permits a large volume of fuel to be burned in a relatively small horizontally dimensioned firebox.

The spacing of the orifices 13 along the burner 11, while not critical, should be maintained close enough for crossignition along the burner, but far enough apart so that the jets from the orifices 31 do not immediately coalesce into a single flow adjacent the burner. Eventually the flames will join, but at a substantial distance above the burner orifices.

For the same reason, it is desired that the tabs 28 and 29 be crosswise of the burner, rather than longitudinal thereof, so that the slow moving gas 33 will be at the sides of the orifices and will have less tendency to coalesce with the slower moving gas of the next adjacent orifice.

The angle which the tabs 28 and 29 make with the top wall 18 is also not critical, but may be varied widely within the spirit of the invention. By way of example only and in no way to be considered as limiting, in one physical embodiment the orifices 31 were placed on centers spaced approximately /2 inch apart and the tabs 28 and 29 met the top wall 18 at an angle of substantially 60". Further by way of example and not in any way limiting, in this exemplification the tabs 28 and 29 were aproximately A inch wide and approximately & inch long from their edges to their bend lines 34 and 35.

While a certain preferred embodiment of this invention has been specifically illustrated and described, it will be understood that the invention is not limited thereto, as many variations will be apparent to those skilled in the art, and the invention is to be given its broadest interpretation within the terms of the following claims.

I claim:

1. A compact, elongated, sheet-metal gas burner substantially rectangular in cross-section with the longer transverse axis disposed vertically so that a narrow side forms the horizontal top wall of the burner and with a chamber provided beneath the top wall for a gaseous fuel mixture to be fed from the burner;

means providing an opening for the entrance of fuel gas and secondary air into said burner chamber;

a plurality of orifices spaced longitudinally of said burner along its top wall through which the fuel mixture is fed to be burned, each said orifice being of nonuniform configuration and providing a main flow port through which the fuel mixture may flow in a high velocity jet and a restricted passage portion through which flow of the fuel mixture is reduced in velocity whereby said main high-velocity jet may flow at a speed substantially higher than the rate of propagation of ignition in the fuel mixture while flame is self-maintained in the slower moving fuel mixture which, in turn, serves to maintain the jet ignited;

each of said orifices being formed by a pair of tabs struck from and bent at an acute angle upwardly from the top wall of the burner to provide an unrestricted main velocity port therebetween, with flow sidewise of the tabs producing the slower moving fuel mixture which maintains the combustion flame;

said tabs being cut apart and bent upwardly along lines 5 2. A compact, elongated, sheet-metal gas burner substantially rectangular in cross-section with the longer transverse axis disposed vertically so that a'narrow side forms the horizontal top wall of the burner with a chamber therebeneath for a gaseous fuel mixture to be fed from the burner; I

means providing an opening atone end of said burner for the entrance of fuel gas and secondary air into the burner chamber;

a plurality of orifices spaced longitudinally of the burner along'its top wall, each of said orifices being formed by two oppositely inclined tabs struck from and bent upwardly from the top wall of the burner and providing an unrestricted passage for main flow of the gaseous fuel mixture therebetween;

the axes of said tabs lying substantially in the same plane as the longitudinal axis of the burner;

the spaces between the side edges of the tabs and the top wall of the burner being unrestricted but progressively decreasing towards the juncture of the bases of the tabs with the top wall of the burner, whereby flame-maintaining portions of the fuel mixture exit sidewise of the tabs with their velocity progressively reduced towards said tab and top wall junctures to values below the speed of propagation of ignition on the fuel mixture whereby said flamemaintaining portions maintain the main fuel flow ig nited and prevent flame-out.

3. The gas burner defined in claim 2 in which:

said orifices being spaced along the length of the burner body at a spacing close enough to provide for cross firing along the burner when the fuel mixture flowing from one orificeis ignited and far enough apart to prevent coalescing of the individual jets from the: ori fiees into a single jet adjacent the burner.

4. The gas burner defined in claim 2 in which v tabs meet the top wall of the burner at interior acute angles whose corners effect the greatest restriction and'lowering of the velocity of the side-exiting, slower-moving,- flame maintaining portions of the fuel mixture.

5. The gas burner defined in claim 2, in whic'hsaid tabs are impervious to prevent flow of the fuel mixture therethrough longitudinally of the burner so that the fuel mixture leaves the burner only in the form of individual jets which do not coalesce until they are a substantial distance above the top wall of the burner.

6. The burner defined in claim 2, in which said slowermoving, flame-maintaining portions of the fuel mixture exit only sidewise of the burner to prevent their coalescing longitudinally of the burner until they are a substantial distance above the top wall of the burner.

References Cited UNITED STATES PATENTS 2,041,348 5/1936 Johnson. 2,044,528 6/1936 Guhl 158-992 X 2,558,057 6/1951 Mun 158-113 X JAMES W. WESTHAVER, Primary Examiner.

US. Cl. X.R. 

